Tensleep Sandstone

The Tensleep Sandstone is a geological formation of Pennsylvanian to very early Permian age in Wyoming.

The formation is composed of fine- to medium-grained sandstone, light gray and yellowish gray; generally slightly to moderately calcareous; some dolomite and sandy dolomite beds; mostly thick to massive sets of low-angle, wedge-planar crossbeds of dunes. Forms cliffs 61-91m (200-300 feet) thick.

Trace fossils
In 1932 Edward Branson and Maurice Mehl reported the discovery of a fossil trackway in the formation. A new ichnospecies, Steganoposaurus belli, was erected for these footprints. The tracks were probably made by a web-footed animal slightly less than three feet long. This creature was originally presumed to be an amphibian, but the toe prints it left behind were pointed like a reptile's rather than round like an amphibians. The actual trackmaker may have been similar to the genus Hylonomus. The ichnogenus Tridentichnus are similar footprints preserved in the Supai Formation of Arizona.